After update to Joomla 3.1.4 or later, some some extensions that depend on the native autoloader, with a working code before, may stop working.
Fatal error: Class 'JBrowser' not found in path/to/file.php on line XY
This issue only affects some 3rd party extensions in Joomla! versions 3.1.4 and higher
An instance of Joomla! Core using JBrowser has been removed causing it not to be automatically loaded on all pages.
Change the source code to something similar as below.
$browser = JBrowser::getInstance(); //...
To this (with legacy way to load classes):
JLoader::import('joomla.environment.browser') // Add this linecode $browser = JBrowser::getInstance(); //...